1. Field of the Invention
The invention relates to a method for manufacturing a shaft sleeve, more particularly to a method for manufacturing a damping shaft sleeve.
2. Description of the Related Art
With reference to FIG. 1, a conventional damping shaft sleeve 1 generally includes a shaft tube 11, a bottom wall 12 that extends radially outward from one end of the shaft tube 11, and a surrounding wall 13 that extends from the bottom wall 12 and that surrounds the shaft tube 11. The bottom wall 12 and the surrounding wall 13 cooperate to define a substantially asymmetrical and annular groove 14. The conventional damping shaft sleeve 1 is adapted to be sleeved around a shaft (not shown) so as to reduce power loss of the shaft during power transmission as caused by vibration-induced belt jumping.
Initially, the conventional method for manufacturing the conventional damping shaft sleeve 1 is primarily based on turning or milling techniques. However, such method has a relatively low production rate and generates excessive waste material, resulting in a relatively high production cost. Hence, such method has been gradually replaced with a method based on forging techniques.
Referring to FIG. 2, the conventional method for manufacturing a damping shaft sleeve based on the forging techniques sequentially includes a preparing step 21, a base material-forming step 22, a billet-forming step 23, a pre-forming step 24, an annular groove-forming step 25, and a refining step 26. In the preparing step 21, a cylinder bar of the raw material 31 is prepared. In the base material-forming step 22, a base material 32 is formed by forging the raw material 31 that has been subjected to a first annealing and acid-cleaning treatment. The base material 32 has a bell-shaped body 321 and a groove 322 formed at the top of the bell-shaped body 321. In the billet-forming step 23, a billet 33 is formed by forging the base material 32 that has been subjected to a second annealing and acid-cleaning treatment and then inverted so that the groove 322 faces downwards. The billet 33 has a small diameter portion 331 that has two opposite ends, two grooves 332 that are respectively formed at the two opposite ends of the small diameter portion 331, and an annular flange 333 that surrounds and extends outward from one of the opposite ends of the small diameter portion 331. In the pre-forming step 24, the grooves 332 of the billet 33 are shaped and reamed. In the groove-forming step 25, an asymmetrical annular groove 14 that has an uneven depth is formed in the annular flange 333 of the billet 33 by a third annealing and acid-cleaning treatment. Finally, in the refining step 26, the grooves 332 on the small diameter portion 331 of the billet 33 are made to communicate with each other so as to form a through hole that extends through the small diameter portion 331 and that has a hexagonal (or toothed) cross-section.
In view of the foregoing, the conventional method for manufacturing the conventional damping shaft sleeve 1 involves multiple annealing treatments, multiple acid-cleaning treatments and multiple forging processes that have to be carried out after the material to be forged is molten. Each of the annealing treatments requires heating of the material, maintaining the temperature of the material and so on, and the acid-cleaning treatment for removing oxide layers formed in the annealing treatment. Thus, the annealing treatments, the acid-cleaning treatments, and subsequent waste water treatment consume much time, energy and money, and there is room for improvement.